There is an image forming apparatus which prints an image on a sheet with an erasable coloring material for recycling of the sheet. In addition, there is an image erasing apparatus which erases an image printed with the erasable coloring material for reuse of the sheet and puts a mark showing the number of times erasing has been carried out on the sheet. However, the erasable coloring material remains on the sheet in a transparent state, even when the image formed with the erasable coloring material is erased by the erasing apparatus. If a coloring material of the mark is put on the erasable coloring material that remains, the coloring material of the mark may be repelled by the erasable coloring material.